This invention relates to a fuel injection apparatus for an internal combustion engine and more particularly to an improved control arrangement for a fuel injection system.
In fuel injected engines, it is, of course, extremely important to accurately control the quantity of fuel injected in accordance with the air inducted in order to achieve the optimum fuel/air ratio for a given operating condition of the engine. Various devices have been proposed for measuring the air flow in an induction system of an engine to control the amount of fuel injected. Conventionally, such air flow measuring devices have been large and complicated and have been positioned in the induction system, normally upstream of the point of discharge of the fuel. In one type of flow detector, a flap type arrangement is provided in the intake passage and has a member that swings open to an amount that is determined by the air flow. The angular position of this detector is then measured and used to provide an air flow signal for the fuel injection system. Alternatively, vortex type air flow meters have been positioned in the induction system for determining air flow. Still another type of measuring device employs a hot wire anemometer which provides an electrical resistance wire interposed in the air stream to have its resistance vary in relation to the speed, i.e., cooling effect, of the air flowing through the induction system. The use of such flow meters in the induction system has several disadvantages.
In the first instance, the provision of an air flow measuring device in the induction system can oftentimes reduce the volumetric efficiency of the induction system. Furthermore, such devices substantially increase the size of the induction system. Also, devices of the type aforenoted are not particularly efficient with engines having a low number of cylinders or specifically with single cylinder engines due to the pulsations in the intake flow. Although such pulsations may be reduced to some extent through the use of a plenum chamber, this adds still further to the size of the induction system. Furthermore, if the flow meter is used in conjunction with the internal combustion engine of an outboard motor or other marine application, there is a high likelihood of corrosion in the moving components of the flow meter due to the salt in the atmosphere.
It is, therefore, a principal object of this invention to provide an improved fuel flow control device for the fuel injection system of an internal combustion engine.
It is another object of this invention to provide an improved air flow detecting device for controlling the fuel injection system of an engine.
It is yet another object of this invention to provide a fuel control device for a fuel injection system of an internal combustion engine that accurately controls fuel flow in response to the amount of air flowing through the intake system.
It is a yet further object of this invention to provide a fuel control for a fuel injection system that does not rely upon a device that is interposed in the air induction system.